Led of side view type and the method for manufacturing the same

ABSTRACT

A side view type light emitting diode (LED) and a method of manufacturing the same are disclosed. In one embodiment, the LED includes i) a pair of lead frames, ii) a reflector surrounding the lead frames, wherein a groove is defined in the reflector, wherein the reflector comprises a plurality of walls surrounding the groove, and wherein at least two walls of the groove face each other, iii) an LED chip mounted in the groove and electrically connected to the lead frames and iv) a lens array contained in the groove.

RELATED APPLICATIONS

This application claims priority to and is a divisional application ofU.S. application Ser. No. 11/906,869, filed Oct. 4, 2007, which is acontinuation application, and claims the benefit under 35 U.S.C. §§120and 365 of PCT Application No. PCT/KR2006/004447, filed on Oct. 30,2006, both of which are hereby incorporated by reference.PCT/KR2006/004447 also claimed the priority of Korean Patent ApplicationNo. 10-2005-0106916, filed on Nov. 9, 2005, in the Korean IntellectualProperty Office, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a light emitting diode, moreparticularly to a side view type light emitting diode and a method ofmanufacturing the same.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

An aspect of the present invention provides a side view type lightemitting diode and a method of manufacturing the same, in which, with alow cost, the thicknesses of the walls are made to be about 0.04 mm toabout 0.05 mm for an overall thickness of about 0.5 mm or lower,according to the trend of the thickness of the light guide plate in abacklight device decreasing to about 0.5 mm or lower.

Another aspect of the present invention provides a side view type lightemitting diode and a method of manufacturing the same, in which themanufacturing process is simplified by forming straight type electrodeswithout additional processes of folding or bending, etc., when formingthe lead frames, and in which the electrical contact between the leadframes and the conductive pattern on the PCB and the supply ofelectricity are made more efficient by providing cutting-grooves on thelead frames (at the ends of the lead frames), when mounting the sideview type light emitting diode on the PCB.

Another aspect of the present invention provides a side view type lightemitting diode and a method of manufacturing the same, in which theheight of the walls forming the reflectors is minimized, so that thetotal quantity of light emitted is increased, and the occurrence of darkspots is minimized when fitting onto a backlight device of an LCD.Another aspect of the present invention provides a method ofmanufacturing a side view type light emitting diode comprising: (a)providing lead frames which include a cathode terminal and an anodeterminal, (b) forming a reflector which surrounds the lead frames, suchthat portions of the cathode terminal and anode terminal protrude fromboth sides, and which includes a groove open in the upward direction anda wall surrounding the groove, (c) die-attaching an LED chip onto thelead frames inside the groove, (d) bonding the LED chip to the cathodeterminal or to the anode terminal with a conductive wire, (e) dispensinga liquid curable resin into the groove to form a lens part and (f)sawing the walls facing each other using a sawing machine, such that thethicknesses at the upper surfaces are about 0.04 mm to about 0.05 mm.

Here, the lead frames may be formed by punching a copper (Cu) boardplated with silver (Ag) using a press cast, and may includecutting-grooves on both side portions of the outer ends of the cathodeterminal and the anode terminal.

Meanwhile, the reflector may be formed by plastic injection molding suchthat the width of the groove is about 0.3 mm to about 0.35 mm. Also, theinner surface of the wall may be formed to have a predefined inclinationwith respect to the bottom surface.

Any one of the (b) forming, the (c) die-attaching, and the (d) bondingmay further include coating a reflective substance or joining areflective plate of a metal material on the inner surface of the wall.

The liquid curable resin may include liquid epoxy with a fluorescentsubstance mixed in, which may be in correspondence with the color of theLED chip.

Another aspect of the present invention provides a side view type lightemitting diode comprising: a pair of lead frames; a reflector whichsurrounds the lead frames and which includes a groove that is open in anupward direction and a wall that surrounds the groove; an LED chipmounted in the groove and electrically connected by wire bonding to thelead frame; and a lens part filled in the groove, where the walls facingeach other have thicknesses of about 0.04 mm to about 0.05 mm at theupper surfaces.

The pair of lead frames may be in the form of a strip, and the leadframes facing each other may be arranged in a straight typeconfiguration and separated by a predefined gap, and may have portionsprotruding out of the reflector. Here, the portions protruding out ofthe reflector may have a tapered shape, such that the width is narrowertowards the end. Also, the height of the wall may be about 0.25 mm toabout 0.35 mm.

Still another aspect of the present invention provides a side view typelight emitting diode comprising: a pair of lead frames; a reflectorwhich surrounds the lead frames and which includes a groove that is openin an upward direction and a wall that surrounds the groove; an LED chipmounted in the groove and electrically connected by wire bonding to thelead frame; and a lens part filled in the groove, where the height ofthe wall is about 0.25 mm to about 0.35 mm. The reflector may include aplastic material, the side view type light emitting diode may be formedby injection molding, and the inner surface of the wall may be formed tohave a predefined inclination with respect to the bottom surface of thegroove.

The lens part may be formed by curing liquid epoxy that includes afluorescent substance in correspondence with the color of the lightemitted by the LED chip.

Also, the pair of lead frames may be in the form of a strip, and thelead frames facing each other may be arranged in a straight typeconfiguration and separated by a predefined gap, and may have portionsprotruding out of the reflector. Here, the portions protruding out ofthe reflector may have a tapered shape, such that the width is narrowertowards the end.

Still another aspect of the invention provides a method of manufacturinga side view type light emitting diode (LED), the method comprising: (a)providing lead frames comprising a cathode terminal and an anodeterminal, (b) forming a reflector surrounding the lead frames such thatportions of the cathode terminal and anode terminal protrude from bothsides of the reflector, wherein a groove is defined in the reflector,wherein the reflector comprises a plurality of walls surrounding thegroove, and wherein at least two walls of the groove face each other,(c) die-attaching an LED chip on the lead frames inside the groove, (d)bonding the LED chip to the cathode terminal or the anode terminal witha conductive wire, (e) dispensing a liquid curable resin into the grooveto form a lens array and (f) sawing the walls of the groove facing eachother using a sawing machine.

Yet another aspect of the invention provides a side view type lightemitting diode (LED) comprising: i) a pair of lead frames, ii) areflector surrounding the lead frames, wherein a groove is defined inthe reflector, wherein the reflector comprises a plurality of wallssurrounding the groove, and wherein at least two walls of the grooveface each other, iii) an LED chip mounted in the groove and electricallyconnected to the lead frames and iv) a lens array contained in thegroove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view for a typical LED applied to an LCDbacklight device.

FIG. 2 is a front-elevational view illustrating an example of a typicalLED.

FIG. 3 is a cross-sectional view for describing another problem in atypical LED applied to an LCD backlight device.

FIG. 4 is a plan view of a typical side view type light emitting diodearrayed in an LCD backlight device.

FIG. 5 is a flowchart schematically representing a method ofmanufacturing a side view type light emitting diode according to anembodiment of the present invention.

FIG. 6 is a plan view illustrating lead frames according to anembodiment of the present invention.

FIG. 7 is a plan view illustrating the lead frames of FIG. 6 afterforming a reflector on the lead frames.

FIG. 8 is a cross-sectional view across line A-A′ of FIG. 7.

FIG. 9 is a cross-sectional view across line B-B′ of FIG. 7.

FIG. 10 is a cross-sectional view after mounting an LED chip andperforming wire bonding.

FIG. 11 is a perspective view illustrating a side view type lightemitting diode manufactured according to an embodiment of the presentinvention.

FIG. 12 is a perspective view of a side view type light emitting diodeaccording to an embodiment of the present invention.

FIG. 13 is a cross-sectional view across line C-C′ of FIG. 12 fordescribing the arrangement of the lead frames.

FIG. 14 is a cross-sectional view across line D-D′ of FIG. 12 with thewalls of the reflector at a common height h₁.

FIG. 15 is a cross-sectional view across line D-D′ of FIG. 12 with thewalls of the reflector at an advantageous height h₂.

FIG. 16 is a cross-sectional view across line E-E′ of FIG. 12.

FIG. 17 is a perspective view illustrating an example of the side viewtype light emitting diode of FIG. 12 applied to an LCD backlight device.

FIG. 18 is a plan view of FIG. 17.

DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

With reference to FIGS. 1 and 2, the composition of a backlight devicein a liquid crystal display (LCD) in a mobile communication equipment istypically as illustrated in FIG. 1. That is, in a backlight device 10, aflat light guide plate 14 is arranged on the board, and side lightemitting diodes, i.e., LED's 20, are arranged at the sides of this lightguide plate 14. Typically, a plurality of LED's 20 are arranged in theform of arrays. The light L from the LED's 20 incident on the lightguide plate 14 is reflected upwards by means of minute reflectivepatterns or a reflective sheet 16 arranged at the bottom surface of thelight guide plate 14, and is emitted from the light guide plate 14 toprovide a backlight for the LCD panel 18 above the light guide plate 14.

FIG. 2 is a front view showing an example of a typical LED 20 such asthat illustrated in FIG. 1. Referring to FIG. 2, an LED 20 includes acup-shaped groove 28 housing an LED chip 22 (see FIG. 1) within, and apackage body 23 having thin walls 24 at the top and bottom andrelatively thick walls 26 to the left and right of the groove 28. Inorder to guide the light generated at the LED chip 22 to the exterior,the cup-shaped groove 28 is open towards the front of the drawing toform an LED window, which is filled with a transparent resin to seal theLED chip from the exterior. Here, a fluorescent element, etc., may beincluded in the resin for converting a single color light into whitelight. Also, a pair of terminals 29 are installed on both sides of thepackage body 23 to electrically connect the LED chip 22 to an exteriorpower source.

With this composition, the terminals 29 are not superposed with thegroove 28, so that the overall thickness of the LED 20 is reduced.

In particular, there is currently a demand for the reduction ofthickness in LCD backlight devices, and a thickness reduction in theLED's is advantageous for the thickness reduction in backlight devices.At present, there is a demand for a thickness of about 0.6 mm or lowerfor side view type light emitting diodes (LED's) in LCD backlightdevices, and it is expected that the demand will be for thicknesses ofabout 0.5 mm or lower in the future.

However, with the LED 20 having a structure such as that illustrated inFIGS. 1 and 2, it is difficult to ensure a package thickness, i.e.,fitted height, of 0.5 mm or lower. This is because the opening of thegroove 28, i.e., the LED window, requires a certain amount of width forguiding the light generated at the LED chip 22 to the exterior, thewalls 24 at the top and bottom of the LED window also require a certainamount of thickness to ensure a desired strength, and it is difficult tomake this thickness go below a certain amount with only theinjection-molding type of manufacturing method.

Another problem in the typical LED applied to LCD backlight devices isthat the opening of the groove 28, i.e., the LED window is separatedupwards by a thickness t_(h) of the lower wall 24 from the bottom of thelight guide plate 14. Thus, the light L generated at the LED chip 22 andemitted downwards towards the exterior of the groove 28 proceeds along apredetermined length before reaching the reflective sheet 16 at thebottom of the light guide plate 14. This creates first dark spots 33, inwhich the light L is dim, on the reflective sheet 16, to degrade theoverall efficiency of the LCD backlight device.

Meanwhile, with the miniaturization of mobile communication equipment onwhich the LCD backlight device is equipped, there is also a trend ofreducing the thickness of the light guide plate for the LCD backlightdevice. That is, the thickness of the light guide plate is being reducedto about 0.5 mm and lower.

In this case, another problem occurs in the LCD backlight device thatemploys typical LED's, as described below with reference to FIG. 3. Asillustrated in FIG. 3, when the thickness of the light guide plate 14 ais about 0.5 mm or lower, the thickness of the LED's 20 a is madegreater than that of the light guide plate 14 a. Then, a substantialamount of light generated at the LED chip 22 a within the LED 20 a doesnot reach the light guide plate 14 a, and light loss occurs. Thus, toprevent this problem, an LCD backlight device 10 a has reflectors 35installed at the upper ends of the sides of the light guide plate 14 ato guide the light to the inside of the light guide plate 14 a andprevent light loss.

However, this further complicates the composition of the LCD backlightdevice 10 a, as well as its manufacturing process, which in turnincreases the work times and costs.

Moreover, as illustrated in FIG. 4, there are a plurality of side viewtype light emitting diodes, i.e., LED's 20, arranged in the form ofarrays on the board 12 at the sides of the light guide plate 14, wheresecond dark spots 36, in which the light generated at the LED chips 22are dim, exist between the plurality of LED's 20, to also degrade theoverall efficiency of the LCD backlight device.

Furthermore, as the depth of the groove 28 of the LED 20 (i.e., thedistance from the surface of the terminal 29 on which the LED chip 22 ismounted to the upper surface of the wall 24) is typically about 0.6 mmor greater, the number of times the light emitted from LED chip 22 isreflected between the inner surfaces of the walls 24 is high, so thatlight loss is increased.

Embodiments of the side view type light emitting diode and a method ofmanufacturing the same will be described below in more detail withreference to the accompanying drawings. In the description withreference to the accompanying drawings, those components are renderedthe same reference number that are the same or are in correspondenceregardless of the figure number, and redundant explanations are omitted.

FIG. 5 is a flowchart schematically representing a method ofmanufacturing a side view type light emitting diode according to anembodiment of the present invention. In describing the method ofmanufacturing a side view type light emitting diode, the respectiveoperations will be described with reference to FIGS. 6 to 11.

FIG. 6 is a plan view illustrating lead frames according to anembodiment of the present invention, FIG. 7 is a plan view illustratingthe lead frames of FIG. 6 after forming a reflector on the lead frames,FIG. 8 is a cross-sectional view across line A-A′ of FIG. 7, FIG. 9 is across-sectional view across line B-B′ of FIG. 7, FIG. 10 is across-sectional view after mounting an LED chip and performing wirebonding, and FIG. 11 is a perspective view illustrating a side view typelight emitting diode manufactured according to an embodiment of thepresent invention.

First, lead frames 110 (see FIG. 6) are prepared (S1). In thisembodiment, a lead frame plate 110 such as that in FIG. 6 is formed bypunching a copper (Cu) board plated with silver (Ag) using a press cast.Here, it is given a thickness of about 0.2 mm, so that it can releasethe heat generated in the LED chip to the exterior.

A pair of lead frames 111 in the form of a strip is arranged such thatthe ends on the inside facing each other are separated by a predefinedgap G, and the ends on the outside are connected on both sides byconnection pieces 113. One side of the pair of lead frames 111 becomesthe cathode terminal 111 a, while the other side becomes the anodeterminal 111 b.

Meanwhile, cutting-grooves 115 are formed on the outer parts of theportions where the outer ends of the lead frames meet the connectionpieces. The function of the cutting-grooves 115 will be described later.

Second, a reflector 120 (see FIGS. 7 to 9) is formed on the lead frameplate 110 (S2).

A reflector 120 is formed, which surrounds the pair of lead frames 111such that the ends protrude out at both the left and right sides, andwhich has a cup-shaped elongated groove 125 that houses the LED chip 130(see FIG. 10) within, and thin upper and lower walls 121 a, 121 b andrelatively thick left and right walls 123 a, 123 b surrounding it. Thereflector 120 is formed on the upper and lower parts of the pair of leadframes 111, and is formed by a general plastic injection moldingtechnique.

In this embodiment, the upper and lower thin walls 121 a, 121 b are madewith a thickness of about 0.2 mm each, with the distance between theinner surfaces of the upper and lower thin walls 121 a, 121 b beingabout 0.3 mm (the thickness of the bottom surface on which the LED chipis placed) at the bottom of the groove 125.

However, with plastic injection molding, the thickness cannot be madeunder about 0.07 mm for the walls, especially the thin walls at the topand bottom, and the manufacturing cost is increased the more thethickness is decreased, and even if the reflector is manufactured at ahigh cost with about 0.07 mm for the thickness of the walls, there arestill problems remaining, in that the overall thickness of the side viewtype light emitting diode is made greater than about 0.5 mm, to beunable to satisfy the trends for a light guide plate 14 a (see FIG. 3)having a thickness of about 0.5 mm or lower, and that reflectors 35 (seeFIG. 3) may have to be used. A technical solution to these problems isachieved by the final operation of the method of manufacturing a sideview type light emitting diode according to one embodiment of thepresent invention, the sawing of the lead frames and walls (S6, see FIG.5). Detailed descriptions on this will be provided later.

Meanwhile, in consideration of the light emission efficiency of the sideview type light emitting diode, the inner surfaces of the walls 121 a,121 b, 121 a, 121 b are formed to have inclinations, while reflectivesubstances may be coated on or a reflective plate of a metal materialmay be joined to the inner surfaces of the walls 121 a, 121 b, 121 a,121 b.

Third, the LED CHIP 130 (see FIG. 9) is die-attached (S3). In thisembodiment, the LED chip 130 is attached onto the lead frame 111 ainside the groove 125 using conductive paste 133, and an LED chip 130 ofdimensions about 0.24 mm×about 0.48 mm×about 0.1 mm is used.

Fourth, the LED chip 130 is bonded to the lead frame 111 b with aconductive wire 135 (see FIG. 10) (S4). In this embodiment, a gold (Au)wire 135 was used.

While in this embodiment, the LED chip 130 is attached to the lead frame1 a of one side by means of conductive paste 133 and bonded afterwardsto the lead frame 111 b of the other side with a gold (Au) wire 135 forelectrical connection, the case may also be considered in which the LEDchip is attached onto the mold of the reflector 120 between the opposingends at the insides of the pair of lead frames 111 a, 111 b by means ofnon-conductive paste (not shown), with wire bonding respectively to thelead frames 111 a, 111 b of both sides.

Fifth, a lens part is formed in the groove 125 of the reflector (S5).The lens part 137 is formed by dispensing liquid epoxy, mixed with afluorescent substance in correspondence with the color of the LED chip130, in the groove 125.

Meanwhile, while in this embodiment, the lens part 137 was formed bymixing a fluorescent substance in liquid epoxy, the case may also beconsidered in which the lens part 137 is formed by potting thefluorescent substance on the LED chip 130 and afterwards injecting acurable resin such as liquid epoxy into the groove 125 of the reflector.

Finally, the lead frame plate and the walls are sawed (S6). Using asawing machine that utilizes blades, both of the walls 121 a, 121 bfacing each other are sawed along cutting lines C (see FIGS. 7 and 8)such that the thickness of each at the upper surface is about 0.04 mm,whereby the side view type light emitting diode 100 and the method ofmanufacturing the same are completed.

As described above, it is difficult to make the thicknesses of the wallsbe about 0.07 mm or lower with injection molding, so that in thisembodiment, a sawing machine utilizing blades is used to make thethicknesses t₂ of the walls 121 a, 121 b be about 0.04 mm each and tomake the top width t₃ of the groove of the reflector be about 0.32 mm,whereby the overall thickness t (see FIG. 11) of the side view typelight emitting diode is made about 0.4 mm.

By thus radically reducing the overall thickness of the side view typelight emitting diode without incurring high costs, the thickness of theLCD backlight device employing the side view type light emitting diodemay be reduced, to satisfy the trends of using light guide plates ofabout 0.5 mm or lower.

Moreover, by reducing the thicknesses t₂ of the walls 121 a, 121 b toabout 0.4 mm each, the first dark spots 33 (see FIG. 1) may beminimized, to increase light emission efficiency when applying a sideview type light emitting diode based on one embodiment the presentinvention to an LCD backlight device.

Meanwhile, when the lead frames 110 (see FIG. 7) and the reflector 120are sawed along the cutting lines C, the cutting-grooves 115 give thepair of lead frames 111 a, 111 b a tapered shape such that the width isnarrower towards the end, whereby the ends may be formed without sawing.

Thus, the problem in using a copper (Cu) board plated with silver (Ag),of having the plated silver (Ag) detached from the copper (Cu) boardduring sawing, such that the efficiency is degraded in electricalcontact between the lead frames and the conductive patterns on the PCBand in the supply of electricity when mounting the side view type lightemitting diode on the PCB, is resolved for the lead frames.

FIG. 12 is a perspective view of a side view type light emitting diodeaccording to an embodiment of the present invention, FIG. 13 is across-sectional view across line C-C′ of FIG. 12 for describing thearrangement of the lead frames, FIG. 14 is a cross-sectional view acrossline D-D′ of FIG. 12 with the walls of the reflector at a common heighth₁, FIG. 15 is a cross-sectional view across line D-D′ of FIG. 12 withthe walls of the reflector at an advantageous height h₂, and FIG. 16 isa cross-sectional view across line E-E′ of FIG. 12.

Referring to FIGS. 12 and 13, a reflector 120′ is comprised, whichsurrounds the pair of lead frames 111′, such that an end portionprotrudes on both sides, and which includes a cup-shaped groove housingthe LED chip 130′ (see FIGS. 14 to 16) within, and thin walls 121′a,121′b at the top and bottom and relatively thick walls 123′a, 123′b tothe left and right of the groove 125′ surrounding it. The reflector 120′is formed at the upper and lower portions of the pair of lead frames111′, and is typically formed by a general plastic injection moldingtechnique.

As shown in FIG. 13, the pair of lead frames 111′ in the form of a striphave the ends facing each other separated by a predefined gap, and arearranged in a straight type configuration, without any folded or bentsurfaces overall. One side of the pair of lead frames 111′ becomes thecathode terminal 111′a, while the other side becomes the anode terminal111′b. The polarity of each terminal may be changed as necessary.

Also, in order for the plastic mold forming the reflector 120′ tosurround the lead frames 111′ and be vertically connected, such that thelead frames 111′ are stably supported, a portion of the inner sides ofthe lead frames 111′ is made to have a narrower width than that ofeither outer end.

The pair of lead frames 111′ used in this embodiment are formed bypunching a copper (Cu) board plated with silver (Ag) using a press cast,where the lead frames 111′ have a thickness of about 0.2 mm, so thatthey can emit the heat generated in the LED chip to the exterior of theside view type light emitting diode.

Also, each outer end of the pair of lead frames 111′a, 111′b may have atapered shape, such that the width is narrower towards the end.

This is because, this shape may solve the problem of the plated silver(Ag) becoming detached from the copper (Cu) board, when manufacturingthe pair of lead frames 111′a, 111′b by sawing the lead frame plate madeof a copper (Cu) board plated with silver (Ag); it may increase theefficiency of electrical contact with the conductive patterns on thePCB, by providing room for the solder between the PCB and the ends ofthe lead frames, when mounting a side view type light emitting diode100′ based on one embodiment of the present invention on the PCB; and itmay improve the heat-releasing effect through the lead frames, byallowing the side view type light emitting diode to closely adhere tothe PCB.

Referring to FIG. 16, the LED 130′ (about 0.24 mm×about 0.48 mm×about0.1 mm) is mounted on the lead frame 111′a of one side exposed throughthe inside of the groove 125′ of the chip reflector 120′, where the LEDchip 130′ is attached by means of conductive paste 133′ and is bondedwith the lead frame 111′b of the other side by a gold (Au) wire 135′ tobe electrically connected.

Also, instead of attaching the LED chip 130′ onto the lead frame 111′aof one side by means of conductive paste 133′ and afterwards bonding tothe lead frame 111′b of the other side by means of a gold (Au) wire135′, the case may also be considered in which the LED chip is attachedonto the lead frame 111′a of one side by means of non-conductive paste(not shown) and then performing wire bonding respectively with the leadframes 111′a, 111′b of both sides.

Meanwhile, a lens part 137′ is comprised in the groove 125′ of thereflector which protects the LED chip 130′ and the gold (Au) wire 135′.In this embodiment, the lens part 137′ is formed by dispensing a liquidepoxy mixed with a fluorescent substance in correspondence with thecolor of the LED chip 130′. By means of the fluorescent substance, asingle color light may be implemented using an LED chip 130′ that emitsa single color light.

Meanwhile, while in this embodiment the lens part 137′ was formed bymixing a fluorescent substance in liquid epoxy, the case may also beconsidered in which the lens part 137′ is formed by potting thefluorescent substance on the LED chip 130′ and afterwards injecting acurable resin such as liquid epoxy into the groove 125′ of thereflector.

With reference to FIGS. 14 to 18, the following describes why the lightemission efficiency and total light quantity are improved for the caseof using an advantageous height h₂ for the walls of the reflectoraccording to an embodiment of the present invention, in comparison tothe case of using a common height h₁ for the walls of the reflector.

FIG. 14 shows the reflection properties of light emitted from an LEDchip 130′ when the height of the walls 121′ confining the groove 125′ ofthe reflector is set to about 0.6 mm (h₁).

The width t₂′ within the groove 125′ is set to about 0.3 mm inconsideration of the width of the LED chip 130′, and the thickness t₁′at the upper portion of the walls 121′ is set to about 0.1 mm inconsideration of structural stability and injection-molding typemanufacture. Here, the inner surfaces of the walls 121′ are giveninclinations for reflecting light, the inclination angle of which is θ₁.

Here, the light L₁ emitted from the LED chip 130′ reflects off the innersurfaces of the walls 121′ four times, where the reflections cause thelight particles to lose certain amounts of energy due to the collisionswith the inner surfaces of the walls 121′.

FIG. 15 shows the reflection properties of light emitted from an LEDchip 130′ when the height of the walls 121′ confining the groove 125′ ofthe reflector is set to about 0.3 mm (h₂).

When the thickness of the chip is set to a typical value of about 0.1mm, the height of the gold (Au) wire 135′ (see FIG. 16) electricallybonding the LED chip 130′ and the lead frames 111′ typically becomesabout 0.15 mm to about 0.2 mm, and since a range of about 0.25 mm toabout 0.35 mm is advantageous for the height of the lens part toencapsulate these for protection, and in consideration of structuralstability, the height of the walls 121′ is set to about 0.3 mm (h₂).

Here, under the condition that t₁′, t₂′, and t′ are made equal, as inFIG. 14, the inclination angle of the inner surfaces of the wallsbecomes θ₂, where θ₂ is greater than θ₁. According to such increase ofθ₂, the reflection properties of the light emitted from the LED chip130′ are also changed.

That is, the number of reflections of the light L₂ emitted from the LEDchip 130′ on the inner surfaces of the walls 121′ is reduced from four(the number of reflections of L₁, see FIG. 14) to one, and at the sametime, the energy lost due to the collisions of light particles with theinner surfaces of the walls 121′ when a reflection occurs is alsoreduced, whereby the total quantity of light outputted from the sideview type light emitting diode 100′ according to one embodiment of thepresent invention is improved.

Considering the recent trends characterized by demands for the thicknessof the light guide plate to be about 0.5 mm or lower, and under theconditions that decreasing t₁ presents problems in manufacturing methodand cost and decreasing t₂ is limited by the size of the LED chip, thisembodiment increases the inclination angle of the inner surfaces of thewalls by reducing the height of the walls confining the groove of thereflector to up to about 0.3 mm, whereby the total quantity of lightoutputted from the side view type light emitting diode is effectivelyimproved.

FIG. 16 is a cross-sectional view across line E-E′ of FIG. 12, where, inorder to compare the difference in effect between the case of using acommon height of about 0.6 mm (h₁), according to prior art, and the caseof using an advantageous height of about 0.3 mm (h₂), according to anaspect of the present invention, for the height of the walls 123′a,123′b, the former case is illustrated by dotted lines.

As shown in FIG. 16, as the height of the walls 123′a, 123′b is reducedfrom about 0.6 mm (h₁) to about 0.3 mm (h₂), under the condition thatthe thickness t₃′ of the upper surface of the walls 123′a, 123′b is keptconstant, it is seen that θv (view angle), which represents the angle ofthe light emitted to the sides, is increased from θv₁ to θv₂.

FIG. 17 is a perspective view illustrating an example of the side viewtype light emitting diode 100′ of FIG. 12 applied to an LCD backlightdevice, and FIG. 18 is a plan view of FIG. 17.

Referring to FIGS. 17 and 18, a plurality of side view type lightemitting diodes 100′ are arranged in the form of arrays on a board 112adjacent to a side of the light guide plate 114.

Here, according to an aspect of the present invention, θv (view angle)is increased as in FIG. 16, as described above, and as the area of thedark spots 136 that appear on the light guide plate 114 in-between theplurality of side view type light emitting diodes 100′ is reducedcompared to the second dark spots (see FIG. 4) of when typical side viewtype light emitting diodes are fitted, the problem in prior art ofdecreased overall efficiency of the LCD backlight device is resolved.

An example comparison experiment is described below with reference toFIGS. 14 and 15. The overall thickness t′ of the side view type lightemitting diode used in the experiment is about 0.425 mm, the width t₂′of the bottom surface of the groove on which the LED chip 130′ is placedis about 0.3 mm, a blue chip of dimensions about 0.24 mm×about 0.48mm×about 0.1 mm is used for the LED chip 130′, a clear type (D-20-4)die-attaching paste is used to bond with the lead frame 111′b of oneside by means of a 1 mil standard gold (Au) wire 135′, and the lens part137′ was implemented to output white light by dispensing a fluorescentsubstance (about 30%) mixed in a liquid epoxy (YE 1205 A/B epoxy) fromYESMTECH company. Also, the delivered voltage was about 20 mA per LEDchip 130′.

The CAS 140B from the Instrument company of Germany, currently oftenused in the LED industry as an initialization (data calibration)instrument, was used for the measurement instrument, and the measurementposition was set to about 100 mm from the LED chip 130′.

Under the above conditions, the luminances of light were comparedbetween the cases of setting the height of the walls 121′ confining thegroove 125′ of the reflector to be about 0.57 mm (a) and about 0.3 mm(b).

The results of the comparison experiment, as seen in Table 1, is thatthe total quantity of light emitted (i.e. luminance) is increased byabout 10% for the side view type light emitting diode in which theheight of the wall 121′ is about 0.3 mm, compared to the case where theheight is about 0.57 mm.

TABLE 1 <Luminance Comparison Experiment Data According to Wall Height>(a) Height of Wall 121 (b) Height of Wall 121 set to 0.57 mm set to 0.3mm Luminance Wavelength Luminance Wavelength No. (mcd) (nm) (mcd) (nm) 11.05 456.83 1.17 455.67 2 1.08 456.25 1.14 455.75 3 1.07 455.18 1.19454.27 4 1.07 454.66 1.19 454.50 5 1.07 455.07 6 1.06 455.80 Min. 1.05454.66 1.14 454.27 Max. 1.08 456.83 1.19 454.75 Avg. 1.07 456.63 1.17455.05

According to at least one embodiment of the present invention, a sideview type light emitting diode and a method of manufacturing the samecan be provided which has an overall thickness of about 0.5 mm or lower,by sawing the mold that surrounds the lead frames and forms thereflector using blades, such that the thickness of the walls is about0.04 mm to about 0.05 mm.

According to at least one embodiment of the present invention canprovide a side view type light emitting diode and a method ofmanufacturing the same, in which the manufacturing process is simplifiedby forming straight type electrodes without additional processes offolding or bending, etc., when forming the lead frames, and in which theelectrical contact between the lead frames and the conductive pattern onthe PCB and the supply of electricity are made more efficient byproviding cutting-grooves on the lead frames (at the ends of the leadframes), when mounting the side view type light emitting diode on thePCB.

Also, one embodiment of the present invention can provide a side viewtype light emitting diode with which the total quantity of light emittedis improved, by minimizing the height of the walls forming thereflector.

Furthermore, as the height of the walls forming the reflector isminimized, the angle of the light emitted may be increased, whereby theforming of dark spots can be minimized when fitting onto the backlightdevice of an LCD.

While the present invention has been described with reference toparticular embodiments, it is to be appreciated that various changes andmodifications may be made by those skilled in the art without departingfrom the spirit and scope of the present invention, as defined by theappended claims and their equivalents.

1. A side view type light emitting diode (LED) comprising: a pair oflead frames; a reflector surrounding the lead frames, wherein a grooveis defined in the reflector, wherein the reflector comprises a pluralityof walls surrounding the groove, and wherein at least two walls of thegroove face each other; an LED chip mounted in the groove andelectrically connected to the lead frames; and a lens array contained inthe groove.
 2. The side view type light emitting diode of claim 1,wherein the walls of the groove facing each other have thicknesses ofabout 0.04 mm to about 0.05 mm at the upper surfaces.
 3. The side viewtype light emitting diode of claim 1, wherein the pair of lead frameshave the form of a strip, and wherein the lead frames facing each otherare arranged in a straight type configuration and separated by apredefined gap, and have portions thereof protruding out of thereflector.
 4. The side view type light emitting diode of claim 3,wherein the protruding portions have a tapered shape such that the widthbecomes narrower towards the end.
 5. The side view type light emittingdiode of claim 1, wherein the height of the walls is about 0.25 mm toabout 0.35 mm.
 6. The side view type light emitting diode of claim 1,wherein the reflector comprises a plastic material.
 7. The side viewtype light emitting diode of claim 6, wherein the width of the groove isabout 0.3 mm to about 0.35 mm.
 8. The side view type light emittingdiode of claim 1, wherein an inner surface of the wall is inclined withrespect to a bottom surface of the groove.
 9. The side view type lightemitting diode of claim 1, wherein the pair of lead frames have the formof a strip, and wherein the lead frames facing each other are arrangedin a straight type configuration and separated by a predefined gap, andhave portions thereof protruding out of the reflector.
 10. The side viewtype light emitting diode of claim 9, wherein the protruding portionshave a tapered shape such that the width becomes narrower towards theend.